Counterbalancing device



March 14, 1939.

J. F. EATON COUNTERBALANC ING DEVICE Filed April l5, 1938 2 Sheets-Sheet l Ml r' 25 March 14, 1939. J. FI EATON 2,150,822

COUNTERBALANG ING DEVICE Filed April 15, v1958 2 sheets-Sheet 2 Patented Mar. 14, 1939 UNITED STATES COUNTERBALANGING DEVICE John F. Eaton, Tulsa, Okla., assignor to American Steel Derrick Company, Tulsa, Okla.

Application April 15, 1938, Serial No. 202,318

16 Claims.

The present invention relates to improvements in rotary counterbalances designed particularly for oil or other well pumping apparatus to counterbalance the weight of sucker rods and fluid in the well.

I am aware that many counterbalance devices of this general type have been heretofore proposed, but the present invention represents an important departure from these prior devices in relation particularly to the novel design of the crank and the arrangement of the mounting of the counterbalance weights and supporting arms therefor, whereby a less bulky, more economical, more effective and safer construction is obtained.

In carrying out my invention, the primary object in view is the provision of a symmetricallyshaped crank to which a Weight or weights are connected on pivots equally spaced from the crank shaft and arranged with weight pivot and crank shaft centers in alignment, the crank being generally elliptical in configuration and having its periphery in the form of two intersecting arcs drawn with the respective pivots as their centers.

It is further an object to provide the counter'- weights with an arcuate edge corresponding to the cooperating crank periphery and so constructed and arranged as to be adjustably interlocked therewith in various positions to afford counterbalance effects from zero to maximum, either positive or negative according to the Work to be performed.

A further object of the foregoing construction resides in the arrangement of the weights such that the radius of the center of gravity of each weight from the crank shaft center decreases as the weights move away from the wrist-pin hole center line, thereby reducing the radius of gyr'ation v of the weights until zero position is reached. In this manner maximum strain due to centrifugal force is reduced as the weight or weights are adjusted toward zero counterbalance position,an important factor related to eciency and safety in these ponderous devices.

Other and further objects and advantages of the invention will be hereinafter described, and the novel features thereof defined in the appended claims.

In the accompanying drawings,

Figure 1 is a perspective view of my improved counterbalance.

Figure 2 is a front elevation on a somewhat enlarged scale showing in full lines one of the counterweights in maximum negative counterbalancing position and the other weight in maximum positive counterbalancing position, the dotted lines showing one of the wights moved to central or zero counterbalancing position.

Figure 3 is a transverse sectional view on the line 3-3 of Figure 2. Y

Figure 4 is a transverse sectional view on the line 4-4 of Figure 2.

Figure 5 is an enlarged, fragmentary sectional view on the line 5-5 of Figure 2.

Figure 6 is a somewhat diagrammatic plan view showing both of the counterbalancing weights moved to maximum positive counterbalancing position.

Figure '7 is a similar view showing the weights in maximum negative counterbalancing position.

Like reference characters designate corresponding parts in the several figures of the drawings.

Referring particularly to Figures 1 and 2, I denotes a drive shaft suitably driven or rotated in any conventional manner, such as by a reduction gear train, not shown, contained in gear box 2; 20

A power source, not shown, such as a gas engine, electric motor, or any other suitable driving means, may be availed of for operating the gear train. The drive shaft I has secured thereon one or more substantially elliptically-shaped crank members or bodies 3 having crank or wrist-pin openings 4 located on the major axis 5. The peripheral edges of the crank body are formed on two intersecting arcs whose centers are located on the minor axis 6 at opposite sides of the drive 30 shaft I. The peripheral edges 'I and 8 of the body 3 are provided with grooved, radial flanges 9 and I0, as best seen in Figures 3 and 4 of the drawings.

These flanges each have an arcuate wall or shoulder I2 disposed for cooperative engagement with a similar arcuate flange I3 extending inwardly from each of the counterweights I4. The counterweights I4, as best seen in Figures 1 and 2, are secured to supporting arms I5 and I6 by suitable fastening means, such as the bolts II 40 and I8. The supporting arm I5 extends across one face of the body 3 to a point on the minor axis 6 located beyond the center of the drive shaft I and is pivotally mounted at this point on a bolt I9. The counterweight supporting arm I6 likewise extends across the other face of the body 3 in overlapping relation with respect to the arm I5, and has its pivotal center located on the minor axis an equal distance beyond the axial t center of the body 3 and is mounted on a bolt 20. A scale of suitable indicia 2| is disposed along the periphery on each side of the ellipticallyshaped body 3, andincreasing from the Zero mark located on the minor axis to the indication I 0 extending toward the major axis, as best seen in Figure 2, that portion of the indicia disposed on the lower half of the crank body carrying the wrist-pin being designed to indicate a positive counterbalancing effect when the weight is shifted to cause registration of the arrow 22 thereon with this indicia. If the weight is shifted to cause registration'of the arrow with the indicia at the opposite end of the scale ZI, a negative counterbalancing effect is produced.

The outer surfaces 23 and 24 of the weights I4 and the arms I5 and I6 are formed on arcs the radii of which are such that when the weights are shifted to their maximum positive counterbalancing position, as seen in Figure 6, the center of the arc of the two surfaces 23, 23, farthest away from the center of rotation of the body will lie on the axis of rotation of the body, while, on the other hand, when the weights are shifted to their maximum negative counterbalancing position, as seen in Figure 7, the center of the arc of the two surfaces 24, 24, farthest away from the center of rotation of the body will lie on the axisI of rotation of the body.

By arranging the pivotal centers of the weights I4 on the bolts I9 and 20 on the minor axis of the body 3 beyond the axis of rotation thereof the counterweights Aas they move from their maximum counterbalancing positions, as seen in Figure 2, to the minimum counterbalancing or mid position, as disclosed in dotted lines in this figure, the weights are moved radially inward as indicated at 25 which permits a material reduction of the radius of gyration of the weights when they reach their center or Zero positions, thereby reducing the centrifugal force and stressesr in the crank and weights as they are moved to this position. The maximum strain due to centrifugal force exists only when the weights are in their maximum counterbalancing position, and when the weights are set in positions for effecting a lesser counterbalancing effect the radius of gyration is also reduced. Hence, this materially reduces fatigue in the parts and the safety factor against failure is increased. This increases the efficiency of my design, since I operate under maximum stresses only part of the time, that is when maximum counterbalancing effect is desired.` For the average operation of the device, theweights are usually'adjustedto positions somewhere between zero and maximum positions, as shown in Figure l. Y

It is, therefore, possible in view of the above, to effect a considerable saving of material in that the crank may be made slightly less bulky and consequently it` may be constructed more economically than many of the counterbalances now in use. Y f

The arcuate, grooved flanges 9 and I0 are disposed in opposing relation on the opposite edges of the body 3, and a web 26 disposed on the major axis of the body connects these vflanges and constitutes a stop shoulder for limiting the swinging movements of the counterweights I4.

Particular attention is directed to the inclined Y cooperating shouldersrrof the flanges 9, I0 on the body and the flanges I3 on the weights I4. When 4the bolts I8 aretghtened, after adjustment of the counterweights, the cooperation ofthese two surfaces produces a wedging action which securely clamps the anges 9 and I0 between the weight supporting plates I5 and I6 and the weights I4. This wedging `action tends to move the weight slightly inward and transfer a considerable portion'of the radial or centrifugal stresses onto this solid arcuate flange on the periphery of the body.

In the operation of the device, the counter- Weights I4 may be readily shifted by power, and to accomplish this the drive shaft I is rotated until the weight to be adjusted is moved to its lowermost position. The bolts I8 are then loosened, and, if necessary, the bolts l1 are also slacked off. The drive shaft is then rotated slightly to move the body 3 with respect to the weight I4 until the desired relative position is reached, as indicated by the relation of the arrow 22 to the scale 2|. The bolts are then tightened and the cooperative wedging action between the weight and body flanges securely locks the weightsin their adjusted position on the body. By utilizing a comparatively long pivotal support for the weight extending upwardly beyond the pivotal center of the body during the weight adjusting operation, a greater gravitative effect of d the weight is produced, permitting a more positive weight adjustment than is possible with the counterbalances now in use.

By providing negative and positive counterbalancing scales 2| on opposite sides of the minor axis, it is possible to adjust both weights for the desired counterbalancing effect whether it be negative or positive, and, under certain circumstances, when it is desired to effect a zero counterbalance, it is only necessary to move one of the weights to the corresponding position on this scale at the opposite side of the minor axis, Whereupon the weights will equalize each other and no counterbalancing effect will be produced. Under the circumstances, if it is desired to readjust the counterbalance to the first-mentioned position, it is only necessary to shift one weight so that the pointer registers with the indicia corresponding to that of the other scale 2l associated with the other weight. The weights may also be shifted to the extreme opposite positions as limited by the stop shoulders 26, as seen in Figure 2, whereupon a Zero counterbalance is effected, and, at the same time, a maximum radial or outward movement of the weights is produced, thereby effecting a maximumradius of gyration of the weights.

While the specicdetails of the invention havev been herein shown and described, the invention is not confined thereto., as changes and alterations may be made without departing from the spirit thereof asV defined by the appended claims.

What I' claim and desire to secure by Letters Patent is:

1. In a counterbalancing structure of the class described, a rotatable body, and a counterbalancing weight disposed on the body at one-side of the axis of rotation of the body and pivoted to the body at a point on `the opposite side of the axis of rotation of the body and within theV confmes thereof, said weight being shiftable about its pivot toward and away from the axis of rotation of the body. Y

2. In a counterbalance Vofthe class described, a rotatable body, an arm pivoted to the body at one side of the rotative axisA thereof for movement independently of the body and extending across the body to the other side of its axis, and a'counterweight securedl thereto and swingable thereby toward and from a linefpassing through the axis of the arm and the axisof the body.Y

3. In a counterbalance of the 4class described, a substantially elliptically-shaped body .having a vmajor and a minor axisV and rotatable onran axis disposed at substantially the intersection of 151 the major and minor axes, and a pair of counterweights adjustably secured to the body at opposite sides of the major axis and movable along the periphery of the body to opposite sides of the minor axis of the body.

4. In a counterbalance of the class described, a substantially elliptically-shaped body having a central axis of rotation, an adjustable counter- Weight interlockingly secured to the periphery of said body and slidable along the periphery of the body, and means for clamping the weight to the body.

5. In a counterweight of the class described, a rotatable, substantially elliptically-shaped supporting body, a pair of counterweights each secured to the body in spaced relation to its axis of rotation and each independently adjustable to swing in a path adjacent to the periphery of the body, and clamping means on the counterweights for adjustably securing the weights to the body at an adjusted position.

6. In a counterbalancing device of the class described, a body rotatable on a central axis, a pair of counterweights pivoted to the body at opposite sides of its axis and extending across the body to a point beyond the body, stop means for limiting the pivotal movement of said counterweights, and means for securing the counter- Weights to the body.

7. In a counterbalancing device of the class described, a rotatable body, a pair of counterweight sup-porting arms pivotally disposed on the opposite sides of the body at opposite sides of the axis of rotation of the body and extending in op'- posite directions toward each other to points beyond the body, and counterweights disposed on said arms.

8. In a counterbalancing device of the class described, a rotatable body, a pair of counter- Weight supporting arms pivotally disposed on the opposite sides of the body at opposite sides of the axis of rotation of the body and extending in opposite directions toward each other to points beyond the body, counterweights disposed on said body, and means for adjustably securing the counterweights to the body.

9. In a device of the class described, a rotatable body, a pair of counterweight supporting arms pivoted to the opposite sides of the body at diametrically opposite points spaced from` the Vaxis of rotation of the body and extending across each other in overlapping relation to points radially beyond the periphery of the body, counter- Weights secured to said arms, and interlocking means on said Weights and body for a-djustably positioning said weights with respect to the axis of rotation of said body.

10. In a counterbalance of the class described, a rotary supporting body of substantially elliptical shape having a major axis' and a minor axis, the periphery of said body having the form of arcuate flanged surfaces extending from the major axis at one side of the axis of rotation to the major axis at the other side, a pair of counter- Weight supporting arms pivoted to the opposite sides of the body at points coincident with the radius of the peripheral arcs, said arms extending across said body to points beyond its periphery and interlocking along the periphery of said body, counterweights secured to said arms formed with interlocking anges engaging the flanged surfaces on the body, and means for clamping said flanges together to prevent movement of the weights on the body.

11. In a counterbalance for pumping rigs of the class described, a substantially elliptically- 'shaped body having a major axis and a minor axis, an operating crank on said major axis and a rotary support disposed at the intersecting point of the major and minor axes, a pair of peripheral flanges projecting from the periphery of said body to points adjacent the major axis of the body, stop shoulders on said flanges located on the major axis of said body, a pair of counter- Weights each adjustably secured to said flanges and adjustable between the stop shoulders at each side of the major axis, and a supporting arm for each of said Weights secured to the body and extending across the body to a point on the minor axis at the opposite side of the majoraxis.

12. In a counterbalance of the class described, a rotatably mounted supporting body, counterweights each disposed at one side of the axis of rotation of said body and pivotally secured to the body at the opposite sides of the axis of rotation of the body, and interlocking arcuate flanges on the body and counterweight formed on an arc having a center coincident with the pivotal center of the counterweight.

13. In a device of the class described, a rotary substantially ellip-tically-shaped crank having a major axis and a minor axis, an interlocking flange projecting from one face and extending around substantially one-half of the periphery of said crank between the ends of the major axis at opposite sides of the axis of rotation of the body, a second interlocking flange projecting from the other face of said body and extending around the other half of the. body between the ends of the major axis, a web between the ends of said flanges constituting stop means, a pair of countervveight supporting arms each pivoted to the body adjacent one face thereof and extending across the body in overlapping relation, and a counterweight secured to each of said arms having an interlocking flange cooperating with one of the flanges aforesaid on the body and movable to opposite sides of the minor axis of said body.

14. A counterbalance device for crank shafts comprising a crank, having' a Wrist-pin opening, a counterbalance weight pivotally secured tothe crank at a point spaced from the axis of the crank to move toward and from the axis of the crank, said weight being so constructed and arranged that the radius of the center of gravity of said weight decreases as the weight moves away from the Wrist-pin axis, and means for securing the weight at adjusted positions.

15. A counter balance device for crank shafts comprising a crank in the form of an elongated body having an arcuate periphery, the center of the arc of which is located at one side of the crank in the line of the minor axis thereof, a counterbalance Weight cooperating with the arcuate periphery and pivoted at the center of the arc aforesaid to swing to opposite sides of the minor axis, and means for securing the weight in positions at either side of said minor axis for positive or negative counterbalancing effect.

16. A counterbalancing device as claimed in claim 15, wherein the arcuate crank periphery and coacting weight periphery are provided with interlocking tongue and groove elements.

JOHN F. EATON. 

